A new driving method for synchronous rectifiers of LLC resonant converter with zero-crossing noise filter

A new driving method for SR is presented. By applying a zero-crossing noise filter to the MOSFET, the false-triggering of the SR can be effectively eliminated. Moreover, the resistor and the capacitor in the filter can be used as a compensator to solve the duty cycle loss issue caused by the trace inductance of the MOSFET package. Only three passive components are needed in the proposed filter which makes it reliable and easy to implement. Simulation and experimental results show that the zero-crossing noise filter can significantly improve the reliability as well as the efficiency of the power circuit. A prototype of 400 V to 12 V 600 W half bridge LLC resonant converter is built to verify the advantages of the new zero crossing noise filter.